Hong Kong's dismal listings market may be set to get a shot in the arm after two decent-sized state-owned enterprises - Sinopec Engineering and China Galaxy Securities - won approval to issue shares that could raise a combined total of at least US$2.5 billion.

Sinopec Engineering, a construction and engineering unit of China Petroleum Corp (Sinopec), Asia's largest oil refiner, will offer its shares at a price-earnings ratio of more than 10 times, translating into an offer worth between US$1 billion and US$1.5 billion, according to people with direct knowledge of the transactions.

The Beijing-based company, which operates on an asset-light business model, aims to use the fresh capital for overseas expansion, and its offer of new shares to potential cornerstone investors was "well received", according to bankers who asked to remain anonymous because the deals were private.

General investors are expected to get more detailed information later this week, after Sinopec Engineering begins pre-marketing its issue on April 19, followed by a roadshow on May 6 and pricing on May 16.

Joining the latest listings rush, China Galaxy Securities, the mainland's seventh-largest brokerage by assets, plans to raise at least US$1.5 billion in the third quarter in the face of lukewarm stock market conditions at home.

The brokerage firm relies heavily on retail stock trading and hopes to use its capital to expand into the more lucrative margin financing and stock lending business.

The company will start to gauge investor demand in a pre-marketing exercise on April 22.

"Valuing the Galaxy Securities [initial public offering] is tricky, as its Hong Kong-listed peers Haitong and Citic Securities are trading at price-book ratios of 1.2 to 1.35 times, which could put the shares of Galaxy in a less favourable situation," said a banker with direct knowledge of the deal.

Investors often expect shares in listing candidates to be issued at discounts of at least 15 per cent to those of their listed industry rivals when they hit the market. That kind of discount offers a level of comfort to deal-savvy investors who have become wary of the after-market performance of initial public offerings in the past year.

Many of this year's listings have tumbled below their issue prices, most noticeably Chalco Mining, a subsidiary of Aluminum Corp of China (Chalco), which lost more than 25 per cent of its market capitalisation after its listing due to mispricing and poor trading sentiment.

Elsewhere, other listing hopefuls including China Everbright Bank and a number of mainland property firms are looking to tap the market in the second half of the year, but some senior bankers have warned that not all property developer listings will spark investor interest, as some are failing to offer a differentiated investment story, in spite of inexpensive valuations.